Abstract
Barium–lanthanum britholite solid solutions, Ba
10-x
La
x
(PO
4
)
6-x
(SiO
4
)
x
F
2
, with 0 ≤ x ≤ 6 were prepared by solid state reaction in the temperature range of 1200–1400 °C. The powders were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-AES), F-selective electrode, X-ray diffraction (XRD), and Fourier transform infrared (FTIR). In addition, the present study used thermal analysis to follow the apatite formation reaction during the heat treatment. For x ≤ 3, there is formation of a single apatite phase, whereas above this value, the La
2
SiO
5
, La
2
Si
2
O
7
, BaSi
2
O
5
, and Ba
2
La
2
O
5
secondary phases were observed. The variation of the lattice parameters of the apatite phase as a function of x confirmed that the solid solution is discontinuous to either side of x = 3.